I have done this using VBA and DAO. I used the right click and/or double click event to identify a drill down was requested, and then captured the KEY information and ran a parameterised SQL query on a detailed data table using DAO to return the required extract, which I dumped into an output sheet.

Apologies if it sounds convoluted - it works very well. Without this then I would have thought either pivots or groups/outlining/subtotals would be the answer.

2) Uncheck the "Allow editing directly in cells" box - it's in the "Editing Options" part of the screen

Now, if you double click into a linked cell, it should jump to the source, whether it's on the same sheet or a different tab. The only drawback is you lose some functionality in the keyboard editing on the cell but you get used to it - I find it very useful.

(this is on Excel 2007 so things may be in a slightly difference place on 2003):

Insert hyperlink. You can set this up to take you to a cell in the spreadsheet, or to anywhere else in cyberspace. It will change the cell formatting to change the colour and underline the text, but you can change it back to the default format afterwards. I use this for contents pages when I have multiple sheets.